1. Field of the Invention
The present invention relates generally to the field of coupling systems for surgical implants, and more particularly to instruments, tools, and methods for use in installing components of such systems during surgical procedures.
2. Background and Related Art
The use of bone stabilization/fixation devices to align or position bones is well established. Furthermore, the use of spinal bone stabilization/fixation devices to align or position specific vertebrae or a region of the spine is well established. Typically such devices use a coupling assembly to connect or link two or more surgical screws and/or pedicle screws together to stabilize the bone and/or joint around which the screws are fixed. The coupling assembly typically is comprised of a relatively rigid member such as a plate or a rod that is used to couple or join adjacent structures or parts of the anatomy. Once the coupled structures are spatially fixed in position, procedures can be completed, healing can proceed, and the like.
Conventional surgical and/or pedicle screw coupling systems, however, have several drawbacks. Those coupling systems are rather large and bulky, which can result in more tissue damage in and around the surgical site, both from when the coupling system is installed during surgery and from implant induced, post-operative tissue irritation and erosion. The relative bulk of the prior art devices may be particularly relevant in supra-fascial applications. The prior art coupling systems have a rod-receiving device that is delivered to the surgeon already coupled or attached to the head of the surgical screw, which poses two challenges: 1) this prevents certain surgical maneuvers (e.g. placing the screws prior to interbody work); and, 2) increases the carrying cost of the inventory. Further, with traditional systems there is an inability to easily extend a fusion; that is to say that in a revision procedure the existing rod would need to be removed rather than just adding a short rod segment to the end of the coupling system. In addition, some of the prior art coupling systems include locking components (e.g., set screws and the like) that must all be carefully assembled together during the surgical procedure. Further, many traditional surgical screw system designs preclude the ability to be placed percutaneously over a guide wire, which makes these systems more difficult to install and maneuver during surgical procedures, including minimally invasive procedures.
Moreover, prior art devices require that the rod be assembled to the coupling device after the screw is inserted in the bone, which can be disadvantageous at times, whereas the option to assemble the rod to the coupling device outside the wound may prove valuable. Also, existing coupling systems necessitate simultaneous locking of all components, which prevents the ability to properly compress a coupling system along the rod because the angle relative to the surgical screw would change. Yet further still, to accommodate various anatomies and/or misplacement of surgical screws due to simple tolerance variances and/or error, requires a surgeon to bend the rod, thus further increasing cost and complexity. The tools, instruments, and methods available for use with such existing systems may be difficult and complex to use, and may require significant technical skill and experience on the part of the surgeon to achieve desired final results.